I. Field of the Invention
This invention relates generally to a cooling or heating device and more particularly, to a moldable, autoclavable device with directional temperature control properties for cooling body organs and parts during surgery or transporting or alternatively heating body parts, such as the ankle, elbow or hands, etc.
II. Discussion of the Prior Art
During many medical procedures, such as open heart surgery, bypass surgery, kidney surgery, surgery of the pancreas, radio or chemotherapy, etc., it is desirable to reduce the temperature of the subject organ so as to slow the metabolic processes thereof during the procedure. The trauma to the organ due to the procedure is thus reduced and the medical professional is also provided additional time to complete the procedure. While the advantages of cryomedicine have been known, the application to many of the foregoing procedures has been hampered by the unavailability of a suitable device which can be used to facilitate organ cooling, but which does not cause damage to the tissue because of overcooling and which does not cause undue cooling of other proximately located body parts. Further, because of the varying organ shapes, it is not only desirable, but necessary, that any such device be moldable so as to conform to the organ's shape and to provide cooling to as large a surface area as possible.
Heretofore, a variety of cold pack devices have been developed for a variety of other applications. These typically have been based upon the principle of an icepack or a frozen water-alcohol mixture contained within a water impermeable container and intended to be held against the object to be cooled. A readily apparent problem with such devices is that when frozen, they solidify and thus do not provide a soft, deformable cooling surface. Above the freezing temperature, they merely act as liquid filled flexible bags that do not hold a shape other than that assumed by the bag when it is placed or held on a surface. The actual cooling area thereby depending upon the weight of the object cooled or the force applied in holding it.
A major drawback of prior art cold packs, therefore, is that they do not permit a shaping of the cold pack so as to maintain a a stable, yet pliable, profile at the temperatures desired for most surgical procedures, e.g. temperatures in range of from 0.degree. C. to -17.degree. C. Another drawback is that they tend to absorb heat rapidly and consequently require frequent replacement. Accordingly, the present invention has been designed to remain moldable and provide cooling for a relatively long period of time, even when placed in relatively warm surroundings. It has also been designed to be capable of being autoclaved. Still further, it has been designed to permit its use as a heating pack.
Examples of some cold pack devices which go beyond a simple icepack can be seen in U.S. Pat. Nos. 3,545,230; 3,736,769; and 4,457,308. The device disclosed in the U.S. Pat. No. 3,545,230 comprises a hydrophilic gel which is coated on a flexible substrate and the substrate retains its flexibility even when frozen. The U.S. Pat. No. 3,736,769 discloses a multi-layered device also containing a core of hydrophilic, alginate containing gel coated layers contained within a polyethylene envelope and having upper and lower walls of different thermal conductivities. The U.S. Pat. No. 4,457,308 describes a liquid nitrogen cooled cushion containing a silica gel and which gel combines with the liquid nitrogen to provide a deformable cushion. None of the cold packs disclosed, however, are useable as heating packs.